Display device and vehicle comprising the same

ABSTRACT

A display device includes a display configured to display a deterioration degree of a secondary battery and a controller. The controller is configured to control the display such that the display does not display the deterioration degree when the deterioration degree is lower than a first level, or configured to control the display such that the display does not display the deterioration degree when the deterioration degree is higher than a second level that is higher than the first level.

INCORPORATION BY REFERENCE

Tis application is a continuation of U.S. application Ser. No.16/541,677 filed Aug. 15, 2019, which claims priority to Japanese PatentApplication No. 2018-197631 filed on Oct. 19, 2018, each of which isincorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a display device and a vehicleincluding the same, and particularly, to a display device that displaysa deterioration degree of a secondary battery, and a vehicle includingthe same.

2. Description of Related Art

Japanese Patent No. 5672778 (JP 5672778 B) discloses a display devicethat displays a value of full charge capacity with a power capacity in afull charge state of a battery (secondary battery) (see JP 5672778 B).

SUMMARY

In the secondary battery, it is known that a reduction in full chargecapacity, an increase in internal resistance, or the like occur overtime, which leads to deterioration of the secondary battery over time.When a deterioration degree of the secondary battery is displayed to auser, some display methods may cause the user to feel anxious about thedeterioration of the secondary battery.

The present disclosure provides a display device that displays adeterioration degree of a secondary battery without causing a user tofeel anxious as much as possible, and a vehicle including the same.

A first aspect of the present disclosure relates to a display deviceincluding a display configured to display a deterioration degree of asecondary battery and a controller. The controller is configured tocontrol the display such that the display does not display thedeterioration degree when the deterioration degree is lower than a firstlevel, or configured to control the display such that the display doesnot display the deterioration degree when the deterioration degree ishigher than a second level that is higher than the first level.

In general, deterioration characteristics of the secondary battery havea tendency that deterioration progresses rapidly at the initial stageimmediately after manufacture, and then is rendered stable. For example,when the secondary battery is used for a power source (power supply fordriving) of a vehicle, there is generally a time lag (for example,several weeks or several months) from when the secondary battery ismanufactured to when the manufactured secondary battery is mounted onthe vehicle and a user starts using the vehicle (secondary battery).Since the above-mentioned deterioration of the secondary batteryprogresses rapidly during the period of time, when a deteriorationdegree of the secondary battery is displayed to the user at the timewhen the user starts using the vehicle (when the vehicle is delivered),it may make the user feel anxious about the fact that the deteriorationof the secondary battery is already in progress even at the time. Withthe display device according to the first aspect, since thedeterioration degree is not displayed when the deterioration degree islower than the first level, it is possible to avoid giving the user theanxiety about the fact that the deterioration of the secondary batteryis already in progress at the time when the user starts using thevehicle (when the vehicle is delivered).

Alternatively, it is supposed that the user cannot determine thereplacement timing of the secondary battery which is deteriorating onlybased on the displaying of the deterioration degree. With the displaydevice according to the first aspect, since the deterioration degree isnot displayed when the deterioration degree is higher than the secondlevel, it is possible to make the user recognize that the replacementtiming of the secondary battery is approaching by not displaying thedeterioration degree.

In the display device according to the first aspect, the controller maybe configured to control the display such that the display does notdisplay the deterioration degree when the deterioration degree is lowerthan the first level. The controller may be configured to control thedisplay such that the display does not display the deterioration degreewhen the deterioration degree is higher than the second level.

With the display device according to the first aspect of the presentdisclosure, for example, when the secondary battery is used for thepower source (power supply for driving) of the vehicle, it is possibleto suppress the uncomfortable feeling of the user due to the fact thatthe deterioration of the secondary battery is already in progress at thetime when the user starts using the vehicle (when the vehicle isdelivered), and when the deterioration is in progress, it is possible tomake the user recognize that the replacement timing of the secondarybattery is approaching.

In the display device according to the first aspect, the controller maybe configured to control the display such that the display displays anotification indicating that the secondary battery is not deterioratedwhen the deterioration degree is lower than the first level.

It is also supposed that some users may feel anxious about the fact thatthe deterioration is not displayed. With the display device according tothe first aspect, since it is specified that the secondary battery isnot deteriorated, it is possible to suppress the anxiety which the userfeels.

In the display device according to the first aspect, the controller maybe configured to control the display such that the display displays anotification prompting replacement of the secondary battery when thedeterioration degree is higher than the second level.

With the display device according to the first aspect, it is possible toexplicitly prompt the user to replace the secondary battery.

In the display device according to the first aspect, the controller maybe configured to control the display such that the display changesdisplay of the deterioration degree stepwise when the display displaysthe deterioration degree.

It is also supposed that some users may feel anxious about the fact thatthe deterioration degree increases sequentially when the deteriorationdegree calculated by a calculating unit is sequentially displayed. Withthe display device according to the first aspect, since the display ofthe deterioration degree is changed stepwise, it is possible to suppressthe anxiety that the user can feel as compared with the case where thedisplay of the deterioration degree is sequentially changed.

A second aspect of the present disclosure relates to a display deviceincluding a display configured to display a deterioration degree of asecondary battery and a controller. The controller is configured tocontrol the display such that the display changes a display mode of thedeterioration degree when the deterioration degree is lower than a firstlevel from that when the deterioration degree is equal to or higher thana first level, or configured to control the display such that thedisplay changes the display mode of the deterioration degree when thedeterioration degree is higher than a second level that is higher thanthe first level from that when the deterioration degree is equal to orlower than the second level.

With the display device according to the second aspect of the presentdisclosure, since the display mode of the deterioration degree ischanged when the deterioration degree is lower than the first level, itis possible to avoid giving the user the anxiety about the fact that thedeterioration degree of the secondary battery is already in progress atthe time when the user starts using the vehicle (when the vehicle isdelivered). Alternatively, with the display device according to thesecond aspect of the present disclosure, since the display mode of thedeterioration mode is changed when the deterioration degree is higherthan the second level, it is possible to make the user recognize thatthe replacement timing of the secondary battery is approaching bychanging the display mode of the deterioration degree.

A third aspect of the present disclosure relates to a display deviceincluding a display configured to display a deterioration degree of asecondary battery and a controller. The controller is configured tocontrol the display such that the display displays, in addition to thedisplay of the deterioration degree, a notification indicating that thesecondary battery is not deteriorated, when the deterioration degree islower than a first level, or configured to control the display such thatthe display displays, in addition to the display of the deteriorationdegree, a notification prompting replacement of the secondary battery,when the deterioration degree is higher than a second level that ishigher than the first level.

With the display device according to the third aspect of the presentdisclosure, since the notification indicating that the secondary batteryis not deteriorated is further displayed when the deterioration degreeis lower than the first level, it is possible to avoid giving the userthe anxiety about the fact that the deterioration degree of thesecondary battery is already in progress at the time when the userstarts using the vehicle (when the vehicle is delivered). Alternatively,with the display device according to the third aspect of the presentdisclosure, since the notification prompting replacement of thesecondary battery is further displayed when the deterioration degree ishigher than the second level, it is possible to make the user recognizethat the replacement timing of the secondary battery is approaching bychanging the display mode of the deterioration degree.

A fourth aspect of the present disclosure relates to a vehicle asecondary battery and a display device configured to include a displayand a controller. The display is configured to display a deteriorationdegree of the secondary battery. The controller is configured to controlthe display such that the display does not display the deteriorationdegree when the deterioration degree is lower than a first level, orconfigured to control the display such that the display does not displaythe deterioration degree when the deterioration degree is higher than asecond level that is higher than the first level.

With the vehicle according to the fourth aspect of the presentdisclosure, it is possible to avoid giving the user the anxiety aboutthe fact that the deterioration degree of the secondary battery isalready in progress at the time when the user starts using the vehicle(when the vehicle is delivered). Furthermore, when the deteriorationdegree is higher than the second level, it is possible to make the userrecognize that the replacement timing of the secondary battery isapproaching.

According to the aspects of the present disclosure, the deteriorationdegree of the secondary battery can be displayed without giving the useranxiety as much as possible.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the present disclosure will be described belowwith reference to the accompanying drawings, in which like numeralsdenote like elements, and wherein:

FIG. 1 is a block diagram of a configuration example of a vehicle towhich a display device is applied according to a first embodiment of thepresent disclosure;

FIG. 2 is a view of an example of a deterioration curve showing that amain battery deteriorates over time;

FIG. 3 is a scatter diagram of an SOC and a battery temperature of themain battery;

FIG. 4 is a histogram of the battery temperature in a certain SOC rangeobtained from the scatter diagram shown in FIG. 3;

FIG. 5 is a view describing an example of a definition of a use area ofthe main battery;

FIG. 6 is a flowchart describing accumulation processing of battery usehistory data;

FIG. 7 is a flowchart showing an example of a procedure of a process ofdisplaying a deterioration degree of the main battery on a display;

FIG. 8 is a view of an example of a display state of the display when acapacity retention rate is higher than the upper limit value;

FIG. 9 is a view of an example of a display state of the display whenthe capacity retention rate is equal to or lower than the lower limitvalue and is equal to or higher than the lower limit value:

FIG. 10 is a view of an example of a display state of the display whenthe capacity retention rate is lower than the lower limit;

FIG. 11 is a flowchart showing an example of a procedure of a process ofdisplaying a deterioration degree, according to a second embodiment;

FIG. 12 is a view of an example of a display state of a displayaccording to the second embodiment when a capacity retention rateexceeds the upper limit:

FIG. 13 is a view of an example of the display state of the displayaccording to the second embodiment when the capacity retention rate islower than the lower limit value;

FIG. 14 is a flowchart showing an example of a procedure of a process ofdisplaying a deterioration degree, according to a third embodiment;

FIG. 15 is a view of an example of a display state of a displayaccording to the third embodiment when a capacity retention rate exceedsthe upper limit;

FIG. 16 is a view of an example of the display state of the displayaccording to the third embodiment when the capacity retention rate islower than the lower limit;

FIG. 17 is a block diagram of a configuration example in which adeterioration degree of a main battery is displayed outside a vehicle;and

FIG. 18 is a block diagram of a configuration example in which adeterioration degree of a main battery is calculated outside a vehicle.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the drawings. In the drawings, the same or likereference signs will be used to designate the same or like components,and therefore description thereof will not be repeated.

First Embodiment

FIG. 1 is a block diagram of a configuration example of a vehicle towhich a display device is applied according to a first embodiment of thepresent disclosure. With reference to FIG. 1, a vehicle 100 includes amain battery 10, a boost converter 22, an inverter 23, a motor generator25, a transmission gear 26, driving wheels 27, and a controller 30.

The main battery 10 is mounted to the vehicle 100 as the drive powersupply of the vehicle 100 (that is, power source). That is, the vehicle100 is an electric vehicle or a hybrid vehicle that employs the mainbattery 10 as the vehicle drive power supply. The hybrid vehicle is avehicle provided with an engine, a fuel cell, or the like (not shown) asthe power source of the vehicle 100 in addition to the main battery 10.The electric vehicle is a vehicle provided with only the main battery 10as the power source of the vehicle 100.

The main battery 10 is formed of a battery set (battery pack) 20including a plurality of battery modules 11. Each battery module 11 isformed to include a secondary rechargeable battery cell, of which atypical example is a lithium ion secondary battery. The lithium ionbattery is a secondary battery in which lithium ions as charge carriersare transported, and may include what is called an all-solid batteryusing a solid electrolyte as well as a general lithium ion secondarybattery using a liquid electrolyte.

The battery pack 20 is provided with a current sensor 15, a temperaturesensor 16, a voltage sensor 17, and a battery monitoring unit 18. Thebattery monitoring unit 18 is formed of an electronic control unit(ECU), for example. Hereinafter, the battery monitoring unit 18 is alsoreferred to as a monitoring ECU 18.

The current sensor 15 detects an input/output current of the mainbattery 10 (hereinafter, also referred to as a battery current Ib). Thetemperature sensor 16 detects temperature of the main battery 10(hereinafter, also referred to as a battery temperature Tb). A pluralityof temperature sensors 16 may be disposed. In this case, the weightedaverage value, the maximum value or the minimum value of thetemperatures detected by the temperature sensors 16 can be used as thebattery temperature Tb, or the temperature detected by a specifictemperature sensor 16 can be used as the battery temperature Tb. Thevoltage sensor 17 detects an output voltage of the main battery 10(hereinafter, also referred to as a battery voltage Vb).

The monitoring ECU 18 receives detection values from the current sensor15, the temperature sensor 16, and the voltage sensor 17, and outputsthe battery voltage Vb, the battery current Ib, and the batterytemperature Tb to the controller 30. Alternatively, the monitoring ECU18 can also store data of the battery voltage Vb, the battery currentIb, and the battery temperature Ib in a built-in memory (not shown).

Further, the monitoring ECU 18 has a function of calculating a state ofcharge (SOC) of the main battery 10 using at least a part of the batteryvoltage Vb, the battery current Ib, and the battery temperature Tb. TheSOC represents the current storage amount to the full charge capacity ofthe main battery 10 as a percentage. It is also possible that thecalculating function of the SOC is provided to the controller 30 (whichwill be described later).

The main battery 10 is connected to the boost converter 22 throughsystem main relays 21 a. 21 b. The boost convener 22 boosts the outputvoltage of the main battery 10. The boost converter 22 is connected tothe inverter 23, and the inverter 23 converts DC power from the boostconverter 22 into AC power.

The motor generator (three-phase motor) 25 receives the AC power fromthe inverter 23 to generate kinetic energy for causing the vehicle totravel. The kinetic energy generated by the motor generator 25 istransmitted to the driving wheels 27. On the other hand, while thevehicle 10 is being decelerated or is being brought to a stop, the motorgenerator 25 converts the kinetic energy of the vehicle 100 intoelectrical energy. The AC power generated by the motor generator 25 isconverted into DC power by the inverter 23, and supplied to the mainbattery 10 through the boost converter 22. In this way, the regenerativepower can be stored in the main battery 10. Accordingly, the motorgenerator 25 is configured to generate a driving force or a brakingforce of the vehicle 100 with exchange of power with the main battery 10(that is, charging/discharging of the main battery 10).

The boost converter 22 can be omitted. In addition, when a DC motor isused as the motor generator 25, the inverter 23 can be omitted.

Furthermore, when the vehicle 100 is the hybrid vehicle in which anengine (not shown) is further mounted as a power source, in addition tothe output of the motor generator 25, the engine output can be used asthe driving force for causing the vehicle to travel. Alternatively, themotor generator 25 (not shown) that generates electrical power by theengine output can be further mounted, and accordingly it is alsopossible to generate charging power of main battery 10 by the engineoutput.

The controller 30 is formed of an electronic control unit (ECU), and isconfigured to include a control unit 31 and a storage unit 32. In thestorage unit 32, various data or programs for operating the control unit31 is stored. The storage unit 32 allows the control unit 31 to read andwrite data and can be provided outside the controller 30.

The controller 30 controls operations of the system main relays 21 a, 21b, the boost converter 22 and the inverter 23. When a start switch (notshown) is switched from on to off, the controller 30 switches the systemmain relays 21 a, 21 b from off to on, or operates the boost converter22 and the inverter 23. Furthermore, when the start switch is switchedfrom on to off, the controller 30 switches the system main relays 21 a,21 b from off to on, or stops operations of the boost converter 22 andthe inverter 23.

The vehicle 100 further includes a display 35. The display 35 isconfigured to display predetermined information regarding the user ofthe vehicle 100 in response to a control command from the controller 30.Specifically, the display 35 displays at least the SOC and thedeterioration degree (which will be described later) of the main battery10 to the user.

Since the SOC represents the current storage amount to the full chargecapacity of the main battery 10 as a percentage, when the deteriorationdegree of the main battery 10 progresses and the charge capacity of themain battery 10 decreases, the actual storage amount (Wh) (it may be Ah,and the same applies below) is reduced even with the same SOC value (forexample, SOC=100%). Therefore, in the first embodiment, as the dataindicating the state of the main battery 10, the deterioration degree ofthe main battery 10 is presented to the user by the display 35 togetherwith the SOC of the main battery 10. The display 35 can be formed of,for example, a touch panel display using a liquid crystal panel.

The vehicle 100 may be configured to have an external charging functionfor charging the main battery 10 by an external power supply 40. In thiscase, the vehicle 100 further includes a charger 28 and charge relays 29a, 29 b.

The external power supply 40 is a power supply provided outside thevehicle, and as the external power supply 40, for example, a commercialAC power supply can be applied. The charger 28 converts the power fromthe external power supply 40 into the charging power of the main battery10. The charger 28 is connected to the main battery 10 through thecharge relays 29 a. 29 b. When the charge relays 29 a, 29 b are on, themain battery 10 can be charged with the power from the external powersupply 40.

The external power supply 40 and the charger 28 can be connected to, forexample, using a charging cable 45. That is, during the mounting of thecharging cable 45, the external power supply 40 and the charger 28 areelectrically connected, and accordingly, the main battery 10 can becharged by the external power supply 40. Alternatively, the vehicle 100may be configured such that power is transmitted between the externalpower supply 40 and the charger 28 in a contactless manner. For example,power is transmitted through a power-receiving coil (not shown) on theexternal power supply side and a power-receiving coil (not shown) on thevehicle side, and accordingly, the main battery 10 can be charged by theexternal power supply 40.

As described above, when AC power is supplied from the external powersupply 40, the charger 28 is configured to have a function of convertingthe power supplied from the external power supply 40 into the chargingpower (DC power) of the main battery 10. Alternatively, when theexternal power supply 40 directly supplies the charging power of themain battery 10, all the charger 28 need to do is to transmit the DCpower from the external power supply 40 to the main battery 10. The modeof the external charging of the vehicle 100 is not particularly limited.

The vehicle 100 travels with charging/discharging of the main battery10. Furthermore, when the vehicle 100 has the external chargingfunction, the main battery 10 is charged while the vehicle 100 isstopped. With such charging/discharging of the main battery 10, the mainbattery 10 deteriorates over time.

FIG. 2 is a view of an example of a deterioration curve showing that themain battery 10 deteriorates over time. In FIG. 2, the horizontal axisshows an elapsed time (year) from the time of manufacturing the mainbattery 10 or the vehicle 100 and the vertical axis shows a capacityretention rate (%) of the main battery 10.

The capacity retention rate of main battery 10 is defined, for example,as a percentage of the current full charge capacity to a full chargecapacity (Wh) (it may be Ah, and the same applies below) when the mainbattery 10 is new (at the time of manufacturing), and is one ofparameters by which the deterioration degree of the main battery 10 canbe quantitatively evaluated. From the above definition, it is understoodthat the higher the capacity retention rate, the lower the deteriorationdegree of the main battery 10, and the lower the capacity retentionrate, the higher the deterioration degree of the main battery 10.

Referring to FIG. 2, as described above, in general, deteriorationcharacteristics of the secondary battery have a tendency that thedeterioration progresses rapidly at the initial stage immediately aftermanufacture, and then is rendered stable. The main battery 10 also hassuch a deterioration progress pace, and the slope of the deteriorationcurve is large at the initial stage immediately after the time ofmanufacture (time 0).

Time t0 is the delivery timing of the vehicle 100, that is, the usestart timing of the vehicle 100 by the user. There is generally a timelag (for example, several weeks or several months) from when the mainbattery 10 is manufactured to when it is mounted on the vehicle 100 andthe user starts using the vehicle 100 (main battery 10) at t0. In thisperiod of time, since deterioration of main battery 10 progressesrapidly, when the deterioration degree of main battery 10 (capacityretention rate C0 (C0<00%)) is displayed at the time (time t0) when theuser starts using the vehicle 100, the user may feel uncomfortable withthe fact that the deterioration of the main battery 10 is already inprogress at the time.

Therefore, in the vehicle 100 according to the first embodiment, whenthe deterioration degree of main battery 10 is lower than the lowerlimit value (first level), that is, when the capacity retention ratio ofmain battery 10 is higher than the upper limit value C1, Thedeterioration degree (capacity retention rate) of the main battery 10 isnot displayed on the display 35. In this case, the display 35 displays amessage indicating that the main battery 10 is not deteriorated. Forexample, C1=80% can beset as the lower limit value of the deteriorationdegree, that is, the upper limit value C1 of the capacity retentionrate.

Then, when the deterioration degree is equal to or higher than the lowerlimit value, that is, when the capacity retention rate is equal to orlower than the upper limit value C1, the deterioration degree (capacityretention rate) is displayed on the display 35. As a result, it ispossible to suppress the uncomfortable feeling of the user due to thefact that deterioration of main battery 10 is already in progress at thetime when vehicle 100 is delivered.

In addition, in a state where deterioration of main battery 10 is inprogress, when the degradation degree is specifically displayed to theuser, the user can confirm the deterioration state of main battery 10.Meanwhile, for example, while 1 it is likely that the user who has ashort trip distance may think that the main battery 10 need not bereplaced yet. When deterioration of main battery 10 is in progress, itis likely that the actual storage amount (Wh) may be greatly reducedeven though the SOC is a sufficient value and the storage amount may besuddenly depleted.

Therefore, in the vehicle 10 according to the first embodiment, when thedeterioration degree of main battery 10 is higher than the upper limitvalue (second level), that is, even when the capacity retention ratio ofmain battery 10 is lower than the lower limit value C2. Thedeterioration degree (capacity retention rate) of the main battery 10 isnot displayed on the display 35. In this case, the display 35 displays amessage prompting replacement of the main battery 10. As a result, theuser can be made to recognize that the replacement timing of the mainbattery 10 is approaching, and the user can be prompted to replace themain battery 10. For example, C2=30% can be set as the upper limit valueof the deterioration degree, that is, the lower limit value C2 of thecapacity retention rate.

Hereinafter, an example of a method of estimating the deteriorationdegree of the main battery 10 will be described with reference to FIGS.3 to 5, and then, display control of the display 35 will be describedwith reference to FIGS. 6 and 7.

FIG. 3 is a scatter diagram of an SOC and a battery temperature Tb ofthe main battery 10. In FIG. 3, the horizontal axis indicates the SOC(%), and the vertical axis indicates the battery temperature Tb (° C.).

Referring to FIG. 3, with respect to battery use history data of themain battery 10 acquired by monitoring ECU 18 at predetermined timing(for example, every hour), combinations of the battery temperature Tband the SOC (%) are plotted as points of scatter diagram. The scatterdiagram shows the trend of the temperature and SOC at which the mainbattery 10 has been used so far. Depending on the previous useconditions of the vehicle 100, the scatter diagram shown in FIG. 3 willbe different.

FIG. 4 is a histogram of the battery temperature Ib in a certain SOCrange obtained from the scatter diagram shown in FIG. 3. FIG. 4 shows,for example, a frequency distribution in a range of every 10 (° C.) ofthe battery temperature Tb, using battery use history data in the rangeof 70 to 80(%) of the SOC in FIG. 3. As described above, a frequencydistribution can be obtained for each range of the SOC (%) in thesimilar way as shown in FIG. 4.

Furthermore, since the appearance frequency of each SOC range can bedetermined, in each SOC range, the occurrence probability for each usearea, which is defined by the combination of the SOC range and thebattery temperature range is performed by multiplying the appearancefrequency and the frequency distribution for each battery temperaturerange similar to FIG. 4, can be determined.

FIG. 5 is a view describing an example of a definition of a use area ofthe main battery 10. Referring to FIG. 5, by combining m (m: naturalnumbers of two or more) SOC ranges in 5(%) increments and n (n: naturalnumbers of two or more) battery temperature ranges in 5 (° C.)increments, n×m use areas R11 to Rmn can be defined.

As described above, the appearance probability of each of the m SOCranges can be determined, and in each SOC range, the frequencydistribution can be determined for the battery temperature range in 5 (°C.) increments. Therefore, occurrence frequencies P11 to Pmncorresponding to use areas R11 to Rmn can be calculated by multiplyingthe appearance probability of each SOC range by the appearance frequencyof each battery temperature range in the SOC range. The total sum of theoccurrence frequencies P11 to Pmn is 1.0.

In general, it is known that the progressing rate of deteriorationincreases over time as the secondary battery continues to have a hightemperature and a high SOC state. Reflecting such characteristics of thesecondary battery, the unit deterioration progress degree when the mainbattery 10 is used for a unit time (for example, one hour) in each ofthe use areas RI to Rmn can be determined in advance in thecorresponding use areas R11 to Rmn. Here, the unit deteriorationprogress degree is indicated by the decrease amount (%/h) of thecapacity retention rate per unit time. In this manner, unitdeterioration progress degrees C.11 to Cnm are stored in advance in thestorage unit 32 in association with the corresponding use areas R11 toRmn.

Furthermore, using the accumulated time Tt (h) from the start of use ofthe main battery 10, the use time in each of the use areas R11 to Rmn isindicated by Tt·P11 to Tt·Pmn. Then, the values obtained by multiplyingthe unit deterioration progress degree C.11 to Cnm by the use time ineach of the use areas R11 to Rmn is summed up, and the deteriorationdegree parameter R of the main battery 10 at the present time iscalculated by the following equation (1).

R=1.0−Tt·(P11·C11+ . . . +Pmn·Cmn)  (1)

The deterioration parameter R corresponds to an estimated value thecapacity retention rate at the present time. R=1.0 (that is, thecapacity retention rate is 100(%)) when the main battery 10 is new. Withrespect to the deterioration parameter R according to the equation (1),it is interpreted that “1.0−R” corresponds to the decrease rate of thefull charging capacity from the initial state (that is, deteriorationdegree). In the following, although the deterioration degree of the mainbattery 10 is estimated using the deterioration parameter R, the lowerthe value of the deterioration parameter R, the higher the deteriorationdegree of the main battery 10.

Furthermore, it is also possible to modify the above equation (1) so asto further estimate the deterioration degree due to charge/dischargecycles using the history data of the battery load (b). The controller 30can estimate the deterioration degree of the main battery 10 at thepresent time by calculating the deterioration degree parameter R asmentioned above. It should be noted that FIG. 3 to FIG. 5 only describean example of the degradation degree estimation process, and when thedeterioration degree parameter R for quantitatively estimating thecurrent degradation degree can be calculated based on the past batteryuse history data, it is possible to estimate the deterioration degreeusing any method.

FIG. 6 is a flowchart describing accumulation process of battery usehistory data. The process according to the flowchart can be executed bythe controller 30.

Referring to FIG. 6, the controller 30 determines whether or not apredetermined time (for example, one hour) has elapsed since theprevious transmission of battery use history data (step S10). Forexample, the elapsed time since the previous collection of battery usehistory data can be measured by a timer (not shown) built in controller30.

The controller 30 continues clocking by the timer until thepredetermined time elapses (NO in step S10)(step S30). The controller 30can obtain the battery current Ib, the battery voltage Vb, the batterytemperature Tb, and the SOC of the main battery 10 at any timing throughthe monitoring ECU 18.

If determination is made in step S10 that the predetermined time haselapsed (YES in step S10), the controller 30 stores battery use historydata of the main battery 10 in the storage unit 32 (step S20). Forexample, data items of the battery temperature Tb, the current value ofSOC, and square value (Ib²) of the battery current Ib indicating abattery load are accumulated as battery use history data. Furthermore,in step S20, the count value by the timer is cleared in response toaccumulating the battery use history data.

The battery use history data can be instantaneous value data at eachtiming after a predetermined time has elapsed. Alternatively, data (forexample, an average value) obtained by statistically processing thebattery temperature Tb, the SOC, the battery load and the like withinthe predetermined time may be stored in the storage unit 32 as batteryuse history data.

The process shown in FIG. 6 is executed when the vehicle 10 travels(when the start switch is on) and when the vehicle 100 is not traveling(when the start switch is off). That is, the process of FIG. 6 isexecuted even when the vehicle 100 is left standing in parking and whenthe vehicle 100 is externally charged, and both the travel time and thenon-travel time of the vehicle 100 are included during the use time ofthe main battery 10.

FIG. 7 is a flowchart showing an example of a procedure of a process ofdisplaying a deterioration degree of the main battery 10 on the display35. The process according to the flowchart can be executed by thecontroller 30.

Referring to FIG. 7, the controller 30 determines whether or notpredetermined deterioration degree update timing arrives (step S110).For example, the deterioration degree update timing can be set to arriveat a certain cycle (for example, every predetermined number of months).For example, in step S110, determination can be made so as to detectwhether or not deterioration degree update timing arrives, each time theprocess shown in FIG. 6 is performed a predetermined number of times.

When the deterioration degree update timing arrives in step S110 (YES instep S110), the controller 30 calculates the current deteriorationdegree (capacity retention rate) of the main battery 10 from the batteryuse history data stored in the storage unit 32 using the above equation(1) (step S120).

Next, the controller 30 determines whether or not the calculatedcapacity retention rate of the main battery 10 is equal to or lower thanthe upper limit value C1 (FIG. 2) (that is, whether or not thedeterioration degree of the main battery 10 is higher than or equal tothe lower limit value (first level) (Step S130). As described above, forexample, C1=80% is set as the upper limit value C of the capacityretention rate.

When the capacity retention rate is higher than the upper limit value C(that is, the deterioration degree is lower than the lower limit value)(NO in step S130), the controller 30 controls the display 35 such thatthe display 35 displays a message indicating that the main battery 10 isnot deteriorated (step S140).

FIG. 8 is a view of an example of a display state of the display 35 whenthe capacity retention rate is higher than the upper limit value C1.That is, FIG. 8 shows an example of the display state of the display 35when the deterioration degree of the main battery 10 is lower than thelower limit value. In FIG. 2, the example of the display state in aperiod of time L1 (time 0 to t1) is shown.

Referring to FIG. 8, in an area 36 of the display 35, the current SOC ofthe main battery 10 is shown. The section of SOC value from the upperlimit value (for example, 100%) to the lower limit value (for example,0%) of the SOC are divided into a predetermined number of segments anddisplayed. In the example, the section of the SOC value is displayedusing ten segments. Since the overcharge and overdischarge of the mainbattery 10 accelerate the deterioration of the main battery 10, theupper limit of the SOC displayed in the area 36 may be lower than 100%(for example 90%). The lower limit of the SOC displayed at the area 36may be a value higher than 0% (for example, 10%).

When the current capacity retention rate (deterioration degree) of themain battery 10 can be shown in the area 37 of the display 35 (dottedline), in a case where the capacity retention rate is higher than upperlimit value C1 (the deterioration degree is lower than lower limitvalue), the capacity retention rate (deterioration degree) is notdisplayed, and a message indicating that the main battery 10 is notdeteriorated is displayed. As an example, the character “good” isdisplayed in the area 37, and it is displayed that the state of the mainbattery 10 is good (not deteriorated).

Referring to FIG. 7 again, when determination is made in step S130 thatthe capacity retention rate of the main battery 10 is equal to or lowerthan upper limit value C1 (that is, the deterioration degree is equal toor higher than the lower limit value) (YES in step S130), the controller30 determines whether or not the capacity retention rate is equal to orhigher than the lower limit value C2 (FIG. 2) (that is, whether or notthe deterioration degree is equal to or lower than the upper limit(second level)) (step S150). As described above, for example, C2=30% isset as the lower limit value C2 of the capacity retention rate.

When the capacity retention rate is equal to or higher than the lowerlimit value C2 (that is, the deterioration degree is equal to or higherthan the upper limit value) (YES in step S150), the controller 30controls the display 35 such that the deterioration degree (capacityretention rate) of the main battery 10 which has been calculated in stepS120 is displayed (step S160).

FIG. 9 is a view of an example of a display state of the display 35 whenthe capacity retention rate is equal to or lower than the upper limitvalue C1 and equal to or higher than the lower limit value C2. That is.FIG. 9 shows an example of the display state of the display 35 when thedeterioration degree of the main battery 10 is equal to or lower thanthe lower limit value and equal to or lower than the upper limit value.In FIG. 2, the example of the display state in a period of time L2 (timet to t2) is shown.

Referring to FIG. 9, in an area 36 of the display 35, the current SOC ofthe main battery 10 is shown as in FIG. 8.

Then, in an area 37 of the display 35, the current capacity retentionrate (deterioration degree) of the main battery 10 is shown.Specifically, the section of the value of the capacity retention ratefrom the upper limit to the lower limit of the capacity retention rateis divided into a predetermined number of segments and displayed. In theexample, the section of the capacity retention rate is displayed usingten segments.

As described above, in the first embodiment, when the deteriorationdegree of the main battery 10 is displayed, the display of thedeterioration degree is changed stepwise. That is, the display 35changes the display of the deterioration degree stepwise with apredetermined number (ten in the example) of segments, instead ofdisplaying the deterioration degree (capacity retention rate) calculatedby the controller 30 as it is. When the deterioration degree calculatedby the controller 30 is sequentially displayed, a user who feels anxiousabout the gradual increase in the deterioration degree is also supposed.By changing the display of the deterioration degree stepwise, theanxiety that the user can feel can be suppressed as compared with thecase of changing the deterioration degree sequentially.

The upper limit and the lower limit of the capacity retention ratedisplayed in the area 37 may be, for example, 100% and 0%, respectively.In this case, when the capacity retention rate reaches the upper limitvalue C1 (for example, 80%), the message display of “Good” shown in FIG.8 is switched to the segment display of the value of capacity retentionrate shown in FIG. 9, and the display state is set such that 80% of thesegment display lights up.

Alternatively, the upper limit and the lower limit of the capacityretention rate displayed in the area 37 may be, for example, the upperlimit C1 (for example, 80%) and the lower limit C2 (for example, 30%)shown in FIG. 2. In this case, when the capacity retention rate reachesthe upper limit value C1 (for example, 80%), the message display of“Good” shown in FIG. 8 is switched to the segment display of the valueof capacity retention rate, and the display state is set such that allsegments of the segment display light up.

Referring to FIG. 7 again, when determination is made in step S150 thatthe capacity retention rate of the main battery 10 is lower than thelower limit value C2 (that is, the deterioration degree is lower thanthe upper limit value) (NO in step S150), the controller 30 controls thedisplay 35 such that the display 35 displays a message promptingreplacement of the main battery 10 (step S170).

FIG. 10 is a view of an example of a display state of the display 35when the capacity retention rate is lower than the lower limit value C2.That is. FIG. 10 shows an example of the display state of the display 35when the deterioration degree of the main battery 10 is higher than theupper limit value. In FIG. 2, the example of the display state in aperiod of time L3 (after t2) is shown.

Referring to FIG. 10, in an area 36 of the display 35, the current SOCof the main battery 10 is shown as in FIGS. 8 and 9.

When the current capacity retention rate (deterioration degree) of themain battery 10 can be shown in the area 37 of the display 35 (dottedline), in a case where the capacity retention rate is lower than lowerlimit value C2 (the deterioration degree is higher than upper limitvalue), the capacity retention rate (deterioration degree) is notdisplayed, and a message prompting replacement of the main battery 10 isdisplayed. As an example, the characters “Replace battery” is displayedin the area 37, and it is displayed that the main battery 10 is neededto be replaced.

In the above description, the SOC of the main battery 10 is divided intoa predetermined number of segments and displayed in the display 35, butinstead of the segment display or in addition to the segment display,the SOC value itself may be displayed.

Further, with regard to the deterioration degree, when the deteriorationdegree of the main battery 10 is included in the range from the lowerlimit to the upper limit on the display 35 (when the capacity retentionrate is included in the range from the upper limit C1 to the lower limitC2), the deterioration degree (capacity retention rate) of the mainbattery 10 is divided into a predetermined number of segments anddisplayed, but instead of the segment display or in addition to thesegment display, the deterioration degree (capacity retention rate)itself may be displayed.

Furthermore, based on the capacity retention rate of the main battery10, the drivable distance (km) of the vehicle 100 at the time of fullcharge of the main battery 10 may be displayed. Since the current fullcharge capacity (kWh) can be calculated from the full charge capacity inthe initial state of the main battery 10 and the current deteriorationdegree (capacity retention rate), for example, the drivable distance(km) of the vehicle 100 at the time of the full charge of the mainbattery 10 can be calculated by multiplying the average electricity cost(km/kWh) of the vehicle 100 by the current full charge capacity (kWh).The drivable distance (km) of the vehicle 100 at the time of the fullcharge depends on the capacity retention rate of the main battery 10,and the drivable distance (km) can be also one parameter that allows thedeterioration degree of the main battery 10 to be quantitativelyevaluated.

As described above, according to the first embodiment, since, when thedeterioration degree of the main battery 10 is lower than the lowerlimit value (first level), the deterioration degree is not displayed onthe display 35, it is possible to suppress the uncomfortable feeling ofthe user due to the fact that deterioration of the main battery 10 isalready in progress at the time of starting using the vehicle 100 (whenthe vehicle is delivery).

Further, according to the first embodiment, since, even when thedeterioration degree of is higher than the upper limit value (secondlevel), the deterioration degree is not displayed on the display 35. Bynot displaying the deterioration degree, it is possible to make the userrecognize that the replacement timing of the main battery 10 isapproaching.

Further, according to the first embodiment, since, when thedeterioration degree is lower than the lower limit value, the messageindicating that the main battery 10 is not deteriorated is specified onthe display 35, it is possible to suppress the anxiety which the userfeels about the fact that the deterioration degree is not displayed.

Further, according to the first embodiment, since, when thedeterioration degree is higher than the upper limit value, the messageprompting replacement of the main battery 10 is displayed on the display35, it is possible to explicitly prompt the user to replace the mainbattery 10.

Further, according to the first embodiment, since, when thedeterioration degree of the main battery 10 is displayed on the display35, the display of the deterioration degree is changed stepwise, it ispossible to suppress the anxiety that the user can feel about theincrease in the deterioration degree as compared with a situation inwhich the deterioration degree is changed sequentially.

Second Embodiment

In the first embodiment described above, when the deterioration degreeof the main battery 10 is lower than the lower limit value (firstlevel), the deterioration degree is not displayed on the display 35, andfurthermore, even when the deterioration degree is higher than the upperlimit (second level), the deterioration degree is not displayed.However, instead of not displaying the deterioration degree, the displaymode of the deterioration degree may be changed when the deteriorationdegree is equal to or higher than the lower limit and equal to or lowerthan the upper limit value.

A configuration of a vehicle to which a display device according to thesecond embodiment is applied is the same as that of the vehicle 100shown in FIG. 1.

FIG. 11 is a flowchart showing an example of a procedure of a process ofdisplaying a deterioration degree, according to a second embodiment. Theflowchart corresponds to the flowchart shown in FIG. 7.

Referring to FIG. 11, the process of steps S210 to S230 and S250 are thesame as the process of steps S110 to S130 and S150 shown in FIG. 7. Whendetermination is made in step S230 that the capacity retention rate ofthe main battery 10 that has been calculated in step S220 is higher thanthe upper limit value C1 (that is, the deterioration degree is lowerthan the lower limit value) (NO in step S230), the controller 30controls the display 35 such that the deterioration degree (capacityretention rate) of the main battery 10 is displayed in a blinking state(step S240).

FIG. 12 is a view of an example of a display state of the display 35when the capacity retention rate is higher than the upper limit value C1in the second embodiment. FIG. 12 corresponds to FIG. 8 described in thefirst embodiment. Referring to FIG. 12, in an area 37 of the display 35,the current capacity retention rate (deterioration degree) of the mainbattery 10 is displayed in a blinking state.

Referring to FIG. 1 again, when determination is made in step S230 thatthe capacity retention rate of the main battery 10 is equal to or lowerthan upper limit value C1 (that is, the deterioration degree is equal toor higher than the lower limit value) (YES in step S230), the controller30 determines whether or not the capacity retention rate is equal to orhigher than the lower limit value C2 (that is, whether or not thedeterioration degree is equal to or lower than the upper limit (secondlevel))(step S250).

When the capacity retention rate is equal to or higher than the lowerlimit value C2 (that is, the deterioration degree is equal to or higherthan the upper limit value) (YES in step S250), the controller 30controls the display 35 such that the deterioration degree (capacityretention rate) of the main battery 10 that has been calculated in stepS220 is displayed (in a lighting state)(step S260).

On the other hand, when determination is made in step S250 that thecapacity retention rate is lower than the lower limit value C2 (that is,the deterioration degree is higher than the upper limit value) (NO instep S250), the controller 30 makes the process proceed to S240, andcontrols the display 35 such that the deterioration degree (capacityretention rate) of the main battery 10 is displayed in a blinking state.

FIG. 13 is a view of an example of the display state of the display 35when the capacity retention rate is lower than the lower limit value C2in the second embodiment. FIG. 13 corresponds to FIG. 10 described inthe first embodiment. Referring to FIG. 13, in an area 37 of the display35, the current capacity retention rate (deterioration degree) of themain battery 10 is displayed in a blinking state.

Although not shown in particular, the blinking state of the display ofthe deterioration degree (FIG. 12) when the capacity retention rate ishigher than the upper limit C1 (NO in step S230) and the blinking stateof the display of the deterioration degree (FIG. 13) when the capacityretention rate is lower than the lower limit value C2 (NO in step S250)may be different from each other.

In the above, when the deterioration degree of the main battery 10 islower than the lower limit value (first level) or when the deteriorationdegree is higher than the upper limit value (second level), the displaymode of the deterioration degree is changed by blinking the display ofthe deterioration degree when the deterioration degree is equal to orhigher than the lower limit value and equal to or lower than the upperlimit value, but it may be changed to a display mode other thanblinking. For example, when the deterioration degree is lower than thelower limit value (first level) or when the deterioration degree ishigher than the upper limit value (second level), the display color, orthe display shade or size of the deterioration degree may be changedwhen the deterioration degree is equal to or higher than the lower limitvalue and equal to or lower than the upper limit value.

As described above, according to the second embodiment, the display modeof the deterioration degree is different between when the deteriorationdegree of the main battery 10 is lower than the lower limit value (firstlevel) or when the deterioration degree is higher than the upper limitvalue (second level) and when the deterioration degree is equal to orhigher than the lower limit value and equal to or lower than the upperlimit value, and thus the same effect as the first embodiment can bealso obtained in the second embodiment.

Third Embodiment

In the first embodiment described above, when the deterioration degreeof the main battery 10 is lower than the lower limit value (firstlevel), the message indicating that the main battery 10 is notdeteriorated is displayed without displaying the deterioration degree onthe display 35. In addition, when the deterioration degree is higherthan the upper limit value (second level), a message promptingreplacement of the main buttery 10 is displayed without displaying thedeterioration degree on the display 35.

In a third embodiment, when the deterioration degree of the main battery10 is lower than the lower limit value (first level), the deteriorationdegree is displayed on the display 35 and the message indicating thatthe main battery 10 is not deteriorated is displayed. In addition, evenwhen the deterioration degree is higher than the upper limit value(second level), the deterioration degree is displayed on the display 35and message prompting replacement of the main battery 10 is displayed.

A configuration of a vehicle to which a display device according to thethird embodiment is applied is the same as that of the vehicle 100 shownin FIG. 1.

FIG. 14 is a flowchart showing an example of a procedure of a process ofdisplaying the deterioration degree, according to the third embodiment.The flowchart also corresponds to the flowchart shown in FIG. 7.

Referring to FIG. 14, the processes of steps S310 to S330, S350 and S360are the same as the processes of steps S110 to S130, S150 and S160 shownin FIG. 7. When determination is made in step S330 that the capacityretention rate of the main battery 10 that has been calculated in stepS320 is higher than the upper limit value C1 (that is, the deteriorationdegree is lower than the lower limit value)(NO in step S330), thecontroller 30 controls the display 35 such that the deterioration degree(capacity retention rate) of the main battery 10 that has beencalculated in S320 and the message indicating that the main battery 10is not deteriorated are displayed (step S340).

FIG. 15 is a view of an example of a display state of the display 35when the capacity retention rate is higher than the upper limit value C1in the third embodiment. FIG. 15 corresponds to FIG. 8 described in thefirst embodiment. Referring to FIG. 15, in the area 37 of the display35, the current capacity retention rate (deterioration degree) of mainbattery 10 is displayed, and the message indicating that the mainbattery 10 is not deteriorated (for example, “Good”) is displayed.

Referring to FIG. 14 again, when determination is made in step S330 thatthe capacity retention rate of the main battery 10 is equal to or lowerthan upper limit value C1 (that is, the deterioration degree is equal toor higher than the lower limit value) (YES in step S330), the controller30 determines whether or not the capacity retention rate is equal to orhigher than the lower limit value C2 (that is, whether or not thedeterioration degree is equal to or lower than the upper limit (secondlevel)) (step S350).

When the capacity retention rate is equal to or higher than the lowerlimit value C2 (that is, the deterioration degree is equal to or higherthan the upper limit value) (YES in step S350), the controller 30 makesthe process proceed to step S360, and causes the display 35 to displaythe deterioration degree (capacity retention rate) of the main battery10 which has been calculated in step S220.

On the other hand, when determination is made in step S350 that thecapacity retention rate is lower than the lower limit value C2 (that is,the deterioration degree is higher than the upper limit value) (NO instep S350), the controller 30 controls the display 35 such that thedeterioration degree (capacity retention rate) of the main battery 10which has been calculated in step S320 and the message promptingreplacement of the main battery 10 are displayed (step S370).

FIG. 16 is a view of an example of the display state of the display 35when the capacity retention rate is lower than the lower limit value C2in the third embodiment. FIG. 16 corresponds to FIG. 10 described in thefirst embodiment. Referring to FIG. 16, in the area 37 of display 35,the current capacity retention rate (deterioration degree) of the mainbattery 10 is displayed, and a message prompting replacement of the mainbattery 10 (for example “Please replace battery”) is displayed.

As described above, in the third embodiment, the same effect as that ofthe first embodiment can be obtained.

Modified Example

In the first embodiment described above, when the deterioration degreeof the main battery 10 is lower than the lower limit value (firstlevel), the deterioration degree is not displayed on the display 35, andfurthermore, even when the deterioration degree is higher than the upperlimit (second level), the deterioration state is not displayed on thedisplay 35. However, the deterioration degree may be set to be displayedon the display 35 merely when the deterioration degree is lower than thelower limit (first level). Alternatively, the deterioration degree maybe set not to be displayed on the display 35 merely when thedeterioration degree is higher than the upper limit value (secondlevel).

When the deterioration degree is set not to be displayed on the display35 merely when the deterioration degree is lower than the lower limitvalue (first level) (merely when the capacity retention rate of the mainbattery 10 is higher than the upper limit value C1), the process ofdisplaying the deterioration degree does not include steps S150 and S170in the flowchart shown in FIG. 7.

On the other hand, when the deterioration degree is set not to bedisplayed on the display 35 merely when the deterioration degree ishigher than the upper limit value (second level)(merely when thecapacity retention rate of the main battery 10 is lower than the lowerlimit value C2), the process of displaying the deterioration degree doesnot include steps S130 and S140 in the flowchart shown in FIG. 7.

Similarly, in the second embodiment described above, when thedeterioration degree of the main battery 10 is lower than the lowerlimit value (first level), the display state of the deterioration degreeis changed, and furthermore, even when the deterioration degree ishigher than the upper limit (second level), the display state of thedeterioration state. However, the display state of the deteriorationdegree may be set to be changed merely when the deterioration degree islower than the lower limit (first level). Alternatively, the displaystate of the deterioration degree may be set to be changed merely whenthe deterioration degree is higher than the upper limit value (secondlevel).

Similarly, in the third embodiment described above, when thedeterioration degree of the main battery 10 is lower than the lowerlimit value (first level), on the display 35, a message is displayed andthe deterioration degree is displayed, and furthermore, even when thedeterioration degree is higher than the upper limit (second level), onthe display 35, the message is displayed and the deterioration degree isdisplayed. However, the deterioration degree may be displayed, and themessage may be displayed on the display 35 merely when the deteriorationdegree is lower than the lower limit (first level). Alternatively, themessage may be displayed and the deterioration degree is displayed onthe display 35 merely when the deterioration degree is higher than theupper limit value (second level).

In each embodiment, the deterioration degree of the main battery 10 andthe message are assumed to be displayed in the display 35 of the vehicle100. However, the displaying may be performed by a system outside thevehicle.

FIG. 17 is a block diagram of a configuration example in which thedeterioration degree of the main battery 10 is calculated outside avehicle. Referring to FIG. 17, in the modified example, a vehicle 100Ahas the same configuration as the vehicle 100 shown in FIG. 1 exceptthat it does not include the display 35 and further includes acommunication unit 50.

The communication unit 50 has a function of executing communication witha service tool 200 provided outside the vehicle 100A. Communication withthe service tool 200 may be wired or wireless. The communication unit 50can be formed, for example, by an on-vehicle wireless communicationmodule.

The service tool 200, which is possessed, for example, by a dealer orthe like, calculates the deterioration degree of the main battery 10from battery use history data of the main battery 10 acquired from thevehicle 100A. In the vehicle 100A, battery use history data of the mainbattery 10 is collected and stored in the storage unit 32, and whencommunication is established between the service tool 200 and thecommunication unit 50, the battery use history data stored in thestorage unit 32 is transmitted to the service tool 200 by thecommunication unit 50.

Then, in the service tool 200, the current deterioration degree of themain battery 10 is calculated from the battery use history data acquiredfrom the vehicle 100A. The deterioration degree is, for example, thecurrent capacity retention rate of the main battery 10, as in the aboveembodiment. The capacity retention rate of the main battery 10 can becalculated using the above equation (1).

In the above embodiment, the deterioration degree of the main battery 10is calculated by the controller 30 of the vehicle 100. However, thedeterioration degree may be calculated by the server 230 outside thevehicle.

FIG. 18 is a block diagram of a configuration example in which adeterioration degree of a main battery 10 is calculated outside avehicle. Referring to FIG. 18, in the modified example, a vehicle 100Bhas the same configuration as the vehicle 100 shown in FIG. 1 exceptthat it further includes a communication unit 50A.

A communication unit 50A forms a communication path 210 with a server230 provided outside the vehicle 100B, and has a function of executingwireless communication. For example, the communication unit 50A can beformed by an on-vehicle wireless communication module.

The vehicle 100B can perform two-way data communication with the server230 by connecting to the wide area communication network 220 (typically,the Internet) through the communication path 210 by the communicationunit 50A. When a predetermined deterioration degree update timingarrives, battery use history data of the main battery 10 is transmittedfrom the vehicle 100B to the server 230.

When the server 230 acquires the battery use history data of the mainbattery 10 from the vehicle 100B, the server 230 calculates thedeterioration degree of the main battery 10 from the acquired batteryuse history data. The deterioration degree is, for example, the currentcapacity retention rate of the main battery 10 as in the aboveembodiment. The capacity retention rate of the main battery 10 can becalculated using the above equation (1). Then, the server 230 transmitsthe calculated deterioration degree (capacity retention rate) to thevehicle 100B.

36) The deterioration degree (capacity retention rate) received by thevehicle 100B is displayed on the display 35. When the deteriorationdegree is lower than the lower limit value (when the capacity retentionrate is higher than the upper limit C1), the message indicating that themain battery 10 is not deteriorated is displayed on the display 35,which is the same as that of the first embodiment. Furthermore, when thedeterioration degree is higher than the upper limit value (the capacityretention rate is lower than the lower limit value C2), the messageprompting replacement of the main battery 10 is displayed on the display35, which is also the same as that of the first embodiment.

Although the display device is applied to the vehicle in embodiments andmodifications, the display device according to the present disclosure isnot limited to the device applied to the vehicle, and can be applied toother devices in which the deterioration degree is displayed.

The embodiments disclosed herein are to be understood as being exemplaryand not to be construed as being limitative of the present disclosure inevery respect. Furthermore, the scope of the present disclosure isindicated in the claims, not in the descriptions of the embodiments, andis intended to include all changes and modifications which do notconstitute departure from the true spirit and scope of the presentdisclosure as claimed in the claims and equivalents thereto.

What is claimed is:
 1. A display device comprising: a display configuredto display a deterioration degree of a secondary battery and configuredto display a notification; and a controller configured to control thedisplay such that the display does not display the deterioration degreeand displays a notification indicating that the secondary battery is notdeteriorated when the deterioration degree is lower than a first level,or is configured to control the display such that the display does notdisplay the deterioration degree and displays a notification promptingreplacement of the secondary battery when the deterioration degree ishigher than a second level that is higher than the first level.
 2. Adisplay device comprising: a display configured to display adeterioration degree of a secondary battery; and a controller configuredto control the display such that the display does not display thedeterioration degree when the deterioration degree is lower than a firstlevel, or configured to control the display such that the display doesnot display the deterioration degree when the deterioration degree ishigher than a second level that is higher than the first level, whereinthe controller is configured to control the display such that thedisplay displays a notification indicating that the secondary battery isnot deteriorated when the deterioration degree is lower than the firstlevel.
 3. The display device according to claim 1, wherein: thecontroller is configured to control the display such that the displaydoes not display the deterioration degree and displays the notificationindicating that the secondary battery is not deteriorated when thedeterioration degree is lower than the first level; and the controlleris configured to control the display such that the display does notdisplay the deterioration degree and displays the notification promptingreplacement of the secondary battery when the deterioration degree ishigher than the second level.
 4. The display device according to claim1, wherein the controller is configured to control the display such thatthe display changes display of the deterioration degree stepwise whenthe display displays the deterioration degree.
 5. The display deviceaccording to claim 1, wherein the controller is configured to controlthe display such that the display displays a notification promptingreplacement of the secondary battery when the deterioration degree ishigher than the second level.